The most relevant trends in the optical networking area are the increase in the network capacity and the increase in transmission reach. In response to the exponential growth of Internet use throughout the world, carriers are installing DWDM (dense wavelength division multiplexing) networks, and attempting to scale-up the existing networks by addition of equipment to support new services. It is estimated that expansion of long haul optical communication networks will be in the order of 70–150%, fueled by ever-growing data, and lately video, traffic. Currently, this expansion continues mostly based on improvements to the current transport technologies.
Carriers are also installing ultra-long reach networks, where regeneration of the signal is effected at 3,000 km or more. The ultra long reach was enabled, among other factors, by the advances in transmitter and receiver design, evolution of optical amplification, employment of distributed Raman amplification combined with various dispersion compensation techniques, new encoding and modulation techniques, digital wrapper technology, etc.
However, the current D/WDM networks use point-to-point (pt—pt) connectivity, which means that all channels are OEO (optical-to-electrical-to-optical) converted at each node, which results in very complex and expensive node configurations. On the other hand, a service needs to be established between two end nodes so that in the majority of cases, OEO conversion at the intermediate nodes adds unjustifiable costs and complexity to the network.
In addition, a point-to-point connectivity impacts negatively on the service activation time, or “time to bandwidth” (TTB). Currently, the waiting time for a new optical service in pt—pt networks is over 120 days. TTB includes two components, the network engineering time and the service activation time.
Network engineering includes generating a physical link and node design that will deliver on the specified network performance so that the provisioning application can establish optimal network operation. The output of the engineering stage feeds into the order process with detailed equipment lists and specifications along with configurations so that the installers know exactly where everything needs to be placed. A pt-pt architecture requires very complex network engineering and planning, resulting in large system turn-up time (in the order of months), involving extensive simulation, engineering and testing. In addition, the pt-pt network requires duplication of equipment for protection/restoration in case of a fault, and, as indicated above equipment for unnecessary OEO conversion.
There is a need to provide a more efficient use of the equipment in the current D/WDM network.
There is a need to break the wavelength engineering bottleneck currently constraining the engineering-to-provisioning ratio, and for wavelengths to became available as a network resource deployable across the network.
If the equipment required to provision a new service is in place, TTB comprises only the service activation time, which includes, besides the time for back office activity and the time for connecting the equipment, the time needed for activating the service. Adding new services in a pt-pt architecture becomes more complex as the number of channels in the network grows, and therefore costly. Furthermore, as the network evolves from linear or ring configurations to mesh connectivity, automation of services becomes a difficult task.
There is a need to provide a network with the ability to automatically route and switch channels from a source node to a destination node with efficient use of OEO conversion.